1. Field of the Invention
The present invention relates generally to methods for forming patterned layers within microelectronic fabrications. More particularly, the present invention relates to methods for forming patterned polyimide layers within microelectronic fabrications.
2. Description of the Related Art
Microelectronic fabrications are formed from microelectronic substrates over which are formed patterned microelectronic conductor layers which are separated by microelectronic dielectric layers.
As microelectronic fabrication integration levels have increased and patterned microelectronic conductor layer dimensions have decreased, it has become increasingly common in the art of microelectronic fabrication to employ when fabricating microelectronic fabrications microelectronic dielectric layers formed of organic polymer dielectric materials. Microelectronic dielectric layers formed of organic polymer dielectric materials are desirable in the art of microelectronic fabrication when fabricating microelectronic fabrications insofar as microelectronic dielectric layers formed of organic polymer dielectric materials may be readily formed employing spin coating methods to form microelectronic dielectric layers of generally lower dielectric constant and generally higher toughness than microelectronic dielectric layers formed of conventional silicon containing dielectric materials, such as but not limited to silicon oxide dielectric materials, silicon nitride dielectric materials and silicon oxynitride dielectric materials.
Of the organic polymer dielectric materials which may be employed for forming dielectric layers within microelectronic fabrications, polyimide organic polymer dielectric materials are particularly common in the art of microelectronic fabrication. Polyimide organic polymer dielectric materials are in turn desirable in the art of microelectronic fabrication insofar as polyimide organic polymer dielectric materials provide particularly impervious and tough dielectric materials when employed, in particular, for forming passivation dielectric layers when forming microelectronic fabrications.
While polyimide organic polymer dielectric materials are thus particularly desirable in the art of microelectronic fabrication for use when fabricating microelectronic dielectric layers within microelectronic fabrications, polyimide organic polymer dielectric materials are nonetheless not entirely without problems within the art of microelectronic fabrication for use when fabricating microelectronic dielectric layers within microelectronic fabrications. In that regard, it has been observed in the art of microelectronic fabrication that microelectronic dielectric layers formed of polyimide organic polymer dielectric materials are often difficult to readily pattern, with optimal dimensional control, when forming patterned dielectric layers within microelectronic fabrications.
It is thus desirable in the art of microelectronic fabrication to provide methods and materials which may be employed for forming within microelectronic fabrications patterned microelectronic dielectric layers formed of polyimide dielectric materials, with enhanced dimensional control.
It is towards the foregoing object that the present invention is directed.
Various methods and materials have been disclosed in the art of microelectronic fabrication for forming with desirable properties within microelectronic fabrications patterned microelectronic dielectric layers formed of polyimide materials.
For example, Fassberg et al., in U.S. Pat. No. 5,242,864, discloses a method for forming, with enhanced smoothing with respect to a cross-sectional profile, a patterned polyimide layer passivating in part a bond pad layer within a microelectronic fabrication. To realize the foregoing object, the method employs when forming the patterned polyimide layer from a blanket polyamic acid layer formed beneath a patterned photoresist layer which defines an aperture which exposes a portion of the blanket polyamic acid layer over the bond pad layer within the microelectronic fabrication a treatment of the portion of the blanket polyamic acid layer exposed within the aperture to form a polyamic acid salt such that upon thermal annealing of the blanket polyamide layer so treated the polyamic acid salt does not form a polyimide, but the remaining portions of the blanket polyamic acid layer do form a polyimide.
Desirable in the art of microelectronic fabrication are additional methods and materials which may be employed for forming, with enhanced dimensional control, within microelectronic fabrications patterned microelectronic dielectric layers formed of polyimide dielectric materials.
It is towards the foregoing object that the present invention is directed.
A first object of the present invention is to provide a method for forming a patterned polyimide layer within a microelectronic fabrication.
A second object of the present invention is to provide a method in accord with the first object of the present invention, wherein the patterned polyimide layer is formed with enhanced dimensional control.
A third object of the present invention is to provide a method in accord with the first object of the present invention and the second object of the present invention, wherein the method is readily commercially implemented.
In accord with the objects of the present invention, there is provided by the present invention a method for forming a patterned polyamic acid layer. To practice the method of the present invention, there is first provided a substrate. There is then formed over the substrate a blanket polyamic acid layer. There is then formed upon the blanket polyamic acid layer a patterned photoresist layer. There is then hardened the patterned photoresist layer to form a hardened patterned photoresist layer. There is then patterned, while employing the hardened patterned photoresist layer as an etch mask layer, the blanket polyamic acid layer to form a patterned polyamic acid layer. There may then be thermally annealed the patterned polyamic acid layer to form a patterned polyimide layer.
The present invention provides a method for forming a patterned polyimide layer within a microelectronic fabrication, wherein the patterned polyimide layer is formed with enhanced dimensional control. The present invention realizes the foregoing object by employing within a microelectronic fabrication when forming from a blanket polyamic acid layer from which is formed a patterned polyamic acid layer from which in turn may be formed a patterned polyimide layer a hardened patterned photoresist layer, rather than an unhardened patterned photoresist layer. By employing the hardened patterned photoresist layer rather than an unhardened patterned photoresist layer, the patterned polyamic acid layer, and consequently also the patterned polyimide layer, are formed with enhanced dimensional control.
The method of the present invention is readily commercially implemented. The present invention employs methods and materials as are generally known in the art of microelectronic fabrication, but employed within the context of a specific ordering to provide the present invention. Since it is thus a specific ordering of methods and materials which at least in part provides the present invention, rather than the existence of methods and materials which provides the present invention, the method of the present invention is readily commercially implemented.